The present invention relates to a universal joint and, more particularly, to a universal joint including a control member for locking an object such as a socket without the risks of injuring a hand of an operator and avoiding damage to the control member due to impingement by an external object when the universal joint is driven by a power drive.
A typical tool for applying rotational force can be coupled with a socket to rapidly tighten or loosen fasteners in an engine compartment of a vehicle. An extension can be coupled between the tool and the socket to reach a fastener difficult to access. In cases where the rotating axis of the fastener is not coincident to the driving axis of the tool, an adaptor such as a universal joint is required.
U.S. Pat. No. 6,092,441 discloses an articulating adapter including first and second drive sections. One of the first and second drive sections is attached to a socket wrench drive, while the other is attached to a socket by a spring-biased ball. The first drive section has a square drive at a first end and a skirt section at a second end. The second drive section includes a square drive at a first end and a rounded base section at a second end. The rounded base section includes an oval shaped bore and is pivotally seated in a cavity in the skirt section of the first drive section. A pivot pin extends through the skirt section of the first drive section and the bore of the second drive section. Thus, the rotating axis of the socket can be at an angle with the driving axis of the power drive by providing the articulating adapter during tightening or loosening of a fastener. An annular collar is provided between the square drive and the rounded base of the second drive section. However, the annular collar is too small to be firmly gripped by the fingers of the operator during tightening or loosening of the fastener, such that the whole articulating adapter wobbles. If an extra element is added to stabilize the articulating adapter, the extra element would injure the hand of the operator during rotation of the articulating adapter and would adversely affect the torque capacity at the annular collar. Furthermore, when the spring biasing the ball for securely coupling the socket has a low elastic coefficient, the coupling force imparted to the ball will be too high, leading to difficulties in coupling or disengaging the socket with or from the articulating adapter. On the other hand, if the spring biasing the ball for securely coupling the socket has a high elastic coefficient, the coupling force imparted to the ball will be too small. As a result, the socket is liable to vibrate and disengage from the articulating adapter when the power drive rotates and, thus, creates vibration.
Thus, a need exists for a universal joint that can operate stably during operation and that has reinforced structural strength while preventing injury to the hand of the operator.